/*
 * Portions Copyright  2000-2009 Sun Microsystems, Inc. All Rights
 * Reserved.  Use is subject to license terms.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 only, as published by the Free Software Foundation.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License version 2 for more details (a copy is
 * included at /legal/license.txt).
 * 
 * You should have received a copy of the GNU General Public License
 * version 2 along with this work; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 * 
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
 * Clara, CA 95054 or visit www.sun.com if you need additional
 * information or have any questions.
 */
package gov.nist.siplite.parser;
import gov.nist.siplite.header.*;
import java.util.*;
import gov.nist.core.*;

/**
 * Parser for SIP Date field. Converts from SIP Date to the
 * internal storage (Calendar).
 */
public class DateParser extends HeaderParser {
    /** Default constructor. */
    DateParser() {}
    
    /**
     * Constructor with initial date header string.
     * @param date initial string to be parsed
     */
    public DateParser(String date) {
        super(date);
    }
    
    /**
     * Constructor with initial lexer engine.
     * @param lexer initial lexer engine
     */
    protected DateParser(Lexer lexer) {
        super(lexer);
    }
    
    /**
     * Invokes parser for date header field.
     * @return the parsed date header
     */
    public Header parse() throws ParseException {
        if (debug) dbg_enter("DateParser.parse");
        try {
            headerName(TokenTypes.DATE);
            int w = wkday();
            lexer.match(',');
            lexer.match(' ');
            Calendar cal = date();
            lexer.match(' ');
            time(cal);
            lexer.match(' ');
            String tzone = this.lexer.ttoken().toLowerCase();
            if (!"gmt".equals(tzone))
                throw createParseException("Bad Time Zone " + tzone);
            DateHeader retval = new DateHeader();
            retval.setDate(cal);
            return retval;
        } finally {
            if (debug) dbg_leave("DateParser.parse");
        }
    }
}
